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To overcome the cost of competition resulting from close social proximity while foraging in a group, individuals may balance their use of private (i.e. acquired from personal sampling) and social (i.e. acquired by watching other individuals) information in order to adjust their foraging strategy accordingly. Reliability of private information about environmental characteristics, such as the spatial distribution of prey, is thus likely to affect individual movement and social interactions during foraging. Our aim was to investigate how movement characteristics of foraging individuals changed as they acquired reliable private information about the spatial occurrence of prey in a foraging context. We allowed guppies (Poecilia reticulata) to develop the reliability of their private knowledge about prey spatial occurrence by repeatedly testing shoals in a foraging task under three experimental distributions of prey: 1) aggregated prey forming three patches located in fixed locations, 2) scattered distribution of prey with random locations, or 3) no prey (used as control). We then applied tracking methods to obtain individual time series of spatial coordinates from which we computed a suite of movement variables reflecting search effort, social proximity and locomotion characteristics during foraging, in order to examine changes occurring over repeated trials and to investigate which best explained foraging success. We show that foraging shoals became more efficient at finding and consuming food over the first three days by increasing their time spent active. Over time, individuals foraging on either scattered or aggregated prey travelled greater distances, showed an increasing distance to their closest neighbour and became slightly more stochastic in their acceleration profile, compared to control individuals. We found that behaviour changed as private information increased over time. Social proximity was the major predictor of foraging success in the absence of prior foraging information, while stochasticity in acceleration and search effort became the most important predictors of foraging success as information increased. In conclusion, we show that individual movement patterns changed as they acquire private information. Contrary to our predictions, the spatial distribution of prey did not affect any of the movement variables of interest. Our results emphasise the importance of information, both private and social, in shaping movement behaviour in animals. Keywords: social foraging, movement, private information, prey spatial distribution, fish.

Top predators may adapt their diets to changes in prey availability where human-induced environmental changes are intense. This long-term study of the breeding-season diet of Golden Eagle (Aquila chrysaetos) in the Strandzha Mountains analyzed shifts in diet caused by the population decline in principal prey species, the tortoises (Testudo hermanni and T. graeca). Tortoises comprised 50.0% of the eagle diet by prey number in the 1990s, but that share collapsed to 5.8% in 2014–2021. During this later interval, Golden Eagles preyed more intensively on lighter-weight prey such as Northern White-breasted Hedgehog (Erinaceus roumanicus, an increrase of 28.2% by number) and Edible Dormouse (Glis glis, an increase of 14.9% by number). Hedgehogs predominated in the diet of an individual eagle nest site for the first time in 1998 and became the principal prey in 2014–2021. Differences in food niche breadth and proportions of mesopredators between tortoise- and hedgehog-dominated individual annual diets were not significant, corresponding to a low level of food stress. The only eagle with an annual diet dominated by Squamata (snakes and lizards) was an exception, having the widest food niche. Young domestic ungulates have almost completely disappeared from eagle diets at the same as the reduction of tortoises, corresponding to a concurrent decline of livestock farming. The results obtained here have relevance to conservation management of both predator and prey populations.

The selection of a safe place to rest at night may be an essential survival strategy for diurnal animals. Despite the importance of parasitoid wasps as consumers in terrestrial ecosystems, their selection of sites to rest and their mortality during the night have not been measured, to the best of our knowledge, reflective of a general lack of understanding of resting behaviours of insects in the field. Here, we used parasitoid wasps of the genus Aphytis (Hymenoptera: Aphelinidae), the highly successful biological control agents of the California red scale, Aonidiella aurantii (Hemiptera: Diaspididae), to study the resting ecology of parasitoids in the field over space and time, considering both external and internal correlates of parasitoid resting behaviour. At night, Aphytis wasps tended to rest on citrus tree leaves, which have a lower host density, but also fewer predators and a greater density of food sources for adult wasps, compared to fruit and branches. On this plant substrate, most of the population avoided predators and survived the night. Aphytis wasps selected leaves on which to rest at night in a nonrandom fashion. They tended to aggregate on leaves with high densities of hosts and food sources (honeydew) and with low densities of potential predators. During the day, wasps with lower egg loads tended to remain on leaves, likely resting and maturing eggs. Overall, our results demonstrate, for the first time, that parasitoids select certain sites at which to rest safely at night. These findings also suggest that the availability of safe resting places could be a valuable resource for beneficial insects in agroecosystems, especially those that have life spans extending over multiple days.

The role of female choice in sexual selection is well established, including the recognition that females choose their mates based on multiple cues. These cues may include intrinsic aspects of a male's phenotype as well as aspects of the environment associated with the male. The role of the spatial location of a potential mate has been well studied in territorial vertebrates. However, despite their role as laboratory models for studies of sexual selection, the potential for insects to choose their mates on the basis of location has scarcely been studied. We studied a natural population of individually tagged crickets (Gryllus campestris) in a meadow in Northern Spain. Adults typically move between burrows every few days, allowing us to examine how pairing success of males can be predicted by the burrow they occupy, independent of their own characteristics. We observed the entirety of ten independent breeding seasons to provide replication and to determine whether the relative importance of these factors is stable across years. We find that both male ID and the ID his burrow affect the likelihood that he is paired with a female, but the burrow has a consistently greater influence. Furthermore, the two factors interact: the relative attractiveness of an individual male depends on which burrow he occupies. Our finding demonstrates a close interaction between naturally and sexually selected traits. It also demonstrates that mate choice studies may benefit from considering not only obvious secondary sexual traits, but also more cryptic traits such as microhabitat choice. We show that female insects choosing to cohabit with a male place more importance on where he lives than on who he is, but the combination of the two is more important still. We know that female birds often choose a male based on the quality of his territory; our 10 years of observing crickets moving around a Spanish meadow to share burrows with members of the opposite sex, reveals insects can do the same.

It has recently been found that iridescence, a taxonomically widespread form of animal coloration defined by a change in hue with viewing angle, can act as a highly effective form of camouflage. However, little is known about whether iridescence can confer a survival benefit to prey postdetection and, if so, which optical properties of iridescent prey are important for this putative protective function. Here, we tested the effects of both iridescence and surface gloss (i.e. specular reflection) on the attack behaviour of prey-naïve avian predators. Using real and artificial jewel beetle, Sternocera aequisignata, wing cases, we found that iridescence provides initial protection against avian predation by significantly reducing the willingness to attack. Importantly, we found that the main factor explaining this aversion is iridescence, not multiple colours per se, with surface gloss also having an independent effect. Our results are important because they demonstrate that even when prey are presented up close and against a mismatching background, iridescence may confer a survival benefit by inducing hesitation or even, as sometimes observed, an aversion response in attacking birds. Furthermore, this means that even postdetection, prey do not necessarily need to have secondary defences such as sharp spines or toxins for iridescence to have a protective effect. Taken together, our results suggest that reduced avian predation could facilitate the initial evolution of iridescence in many species of insects and that it is the defining feature of iridescence, its colour changeability, that is important for this effect.

Abstract Primates understand the meaning of their own and other species’ alarm calls, but little is known about how they acquire such knowledge. Here, we combined direct behavioural observations with playback experiments to investigate two key processes underlying vocal development: comprehension and usage. Especifically, we studied the development of con- and heterospecific alarm call recognition in free-ranging sooty mangabeys, Cercocebus atys, across three age groups: young juveniles (1–2y), old juveniles (3–4y) and adults (> 5y). We observed that, during natural predator encounters, juveniles alarm called to a significantly wider range of species than adults, with evidence of refinement during the first four years of life. In the experiments, we exposed subjects to leopard, eagle and snake alarm calls given by other group members or sympatric Diana monkeys. We found that young juveniles’ locomotor and vocal responses were least appropriate and that they engaged in more social referencing (look at adults when hearing an alarm call) than older individuals, suggesting that vocal competence is obtained via social learning. In conclusion, our results suggest that alarm call comprehension is socially learned during the juvenile stage, with comprehension preceding appropriate usage but no difference between learning their own or other species’ alarm calls. Significance statement Under natural conditions, animals do not just interact with members of their own species, but usually operate in a network of associated species. However, ontogenetic research on primate communication frequently ignores this significant element. We studied the development of con- and heterospecific alarm call recognition in wild sooty mangabeys. We found that communicative competence was acquired during the juvenile stages, with alarm call comprehension learning preceding appropriate vocal usage and with no clear difference in learning of con- and heterospecific signals. We also found that, during early stages of life, social referencing, a proactive form of social learning, was key in the acquisition of competent alarm call behaviour. Our results show that primates equally learn to interpret alarm calls from their own and other species during their early stages of life and that this learning process is refined as the animals mature.

Jason G.H. Londt contributed almost a quarter of the KwaZulu-Natal Museum’s specimens of Cicadidae, including a strong sample of females, and probably the best set to date of African records of predation on cicadas by robber flies. The collection provides evidence that robber flies catch more male cicadas; speculatively, because attacks on the heavier-bodied female fail more often. The metadata derived from these specimens also provide a small gazetteer of Londt’s collecting sites.

Numerous mechanisms can promote competitor coexistence. Yet, these mechanisms are often considered in isolation from one another. Consequently, whether multiple mechanisms shaping coexistence combine to promote or constrain species coexistence remains an open question.Here, we aim to understand how multiple mechanisms interact within and between life stages to determine frequency-dependent population growth, which has a key role stabilizing local competitor coexistence.We conducted field experiments in three lakes manipulating relative frequencies of two Enallagma damselfly species to evaluate demographic contributions of three mechanisms affecting different fitness components across the life cycle: the effect of resource competition on individual growth rate, predation shaping mortality rates, and mating harassment determining fecundity. We then used a demographic model that incorporates carry-over effects between life stages to decompose the relative effect of each fitness component generating frequency-dependent population growth.This decomposition showed that fitness components combined to increase population growth rates for one species when rare, but they combined to decrease population growth rates for the other species when rare, leading to predicted exclusion in most lakes.Because interactions between fitness components within and between life stages vary among populations, these results show that local coexistence is population specific. Moreover, we show that multiple mechanisms do not necessarily increase competitor coexistence, as they can also combine to yield exclusion. Identifying coexistence mechanisms in other systems will require greater focus on determining contributions of different fitness components across the life cycle shaping competitor coexistence in a way that captures the potential for population-level variation.

Objective: The objective of the study was to understand and document socio-economic characteristics, production parameters, challenges and management practices used by Fijian households which keep indigenous chickens.Methods: A survey involving 200 households was carried out in coastal and inland communities of Fiji’s wet and semi-dry ecoregions. Data on the influence of ecoregion and location of households relative to the sea on management practices, challenges and productivity of indigenous chickens were analyzed using logistic regression and general linear model of SAS software.Results: Irrespective of location relative to the sea and ecoregion, households indicated that they kept indigenous chickens for food and income generation. The Welsummer was the most (p>0.05) preferred breed. Households in the semi-dry inland communities had the largest (p0.05) common predator followed by domestic dogs. Most households in the wet ecoregion’s coastal communities housed their chickens at night, whereas communities in semi-dry ecoregion housed their chickens most of the time (p0.05). Households in semi-dry ecoregion were more likely (p>0.05) to sell their chickens at the local market place.Conclusion: The productivity of local chickens in Fiji is low because of feed shortage, predators such as the mongoose and lack of market linkages.

Predatory fish have occasionally been observed preying on birds, sometimes repeatedly, but few studies were able to unravel the overall significance of avian prey in fish diet and the predation impacts on bird populations. We used a control/impact study setup, using a Nature Reserve in northern Italy and a nearby control area, to determine: 1) the contribution of waterbirds to wels catfish diet in the Reserve, 2) the population density of wels catfish in the Reserve and control area and 3) the potential impacts of waterbird depredation by wels catfish on waterbird population trends. Our stable isotope Bayesian mixing model indicated that birds contributed 12.2% (5–27.9%, 50% confidence interval) of the diet of large wels catfish (> 98 cm in total length). Large individuals constituted the majority of the population in the shoreline areas of the reserve in 2013–2019, where the population was stable despite control efforts. Numbers were below detectable levels in the control area. Large wels catfish consumed an average of 224, 148 and 187 kg of birds during the 2019 chick growing period, as estimated through three different bioenergetic models. Compared to the control area, mallard reproductive success was diminished in the Reserve, likely due to higher rates of fish predation, although effects were variable in different years. Overall, our data suggest that high densities of invasive wels catfish might impact waterbird reproductive success through predation on bird chicks, but further studies would be needed to reduce uncertainties related to the intrinsic variability of field ecology data. Our study constitutes a preliminary attempt to assess the potential of introduced wels catfish to affect the conservation value of waterbird protection areas, and should be repeated at broader spatial and temporal scales.

Predation represents an important evolutionary force shaping specific adaptations. Prey organisms present behavioral adaptations that allow them to recognize, avoid, and defend themselves from their predators. In addition to predation, there is a growing consensus about the role of parasitism in the structuring of biological communities. In vertebrates, the effects on hosts include changes in daily activity, feeding, mate selection, reproduction, and modifications in responses to environmental stimuli. These behavioral variations can benefit the parasite (parasitic manipulation), benefit the host, or appear as a side effect of the infection. We evaluated the influence of parasitism on the behavioral and physiological responses of the tuco-tucos of the Talas (Ctenomys talarum Thomas, 1898) to predator cues. We found that individuals exposed to cat odors and immobilization entered less often and spent less time in the transparent arms of elevated maze, exhibiting a preference for protected areas (anxiogenic response). Additionally, we evaluated if the presence of parasites affected antipredatory behaviors in C. talarum (naturally parasitized, deparasitized, or inoculated with Eimeria sp.). We did not find differences among the groups with regards to responses to predator cues. Therefore, while exposure to predator cues triggered a stress response, the manipulation of parasite loads did not modify homeostasis under these experimental conditions.

Intersexual differences in life span (age at death) and aging (increase in mortality risk associated with functional deterioration) are widespread among animals, from nematodes to humans. Males often live shorter than females, but there is substantial unexplained variation among species and populations. Despite extensive research, it is poorly understood how life span differences between the sexes are modulated by an interplay among genetic, environmental and social factors. The goal of our study was to test how sex differences in life span and ageing are modulated by social and environmental factors, and by intrinsic differences between males and females. To disentangle the complex basis of sex differences in life span and aging, we combined comparative data from sex ratios in 367 natural populations of four species of African annual killifish with experimental results on sex differences in life span and aging from eight laboratory populations tested in treatments that varied social and environmental conditions. In the wild, females consistently outlived males. In captivity, sex-specific mortality depended on social conditions. In social-housed experimental groups, male-biased mortality persisted in two aggressive species, but ceased in two placid species. When social and physical contacts were prevented by housing all fish individually, male-biased mortality ceased in all four species. This outcome held across benign and challenging environmental conditions. Fitting demographic survival models revealed that increased baseline mortality was primarily responsible for a shorter male life span in social-housing conditions. The timing and rate of aging were not different between the sexes. No marker of functional aging we recorded in our study (lipofuscin accumulation, proliferative changes in kidney and liver) differed between males and females, despite their previously confirmed association with functional aging in Nothobranchius killifish. We show that sex differences in life span and aging in killifish are driven by a combination of social and environmental conditions, rather than differential functional aging. They are primarily linked to sexual selection but precipitated through multiple processes (predation, social interference). This demonstrates how sex-specific mortality varies among species even within an ecologically and evolutionary discrete lineage and explains how external factors mediate this difference.

Prey may gain fitness benefits from recognizing predators at an early age. Predator cues perceived by gravid prey have the potential to prime offspring to alter their behaviour in the presence of predation threats after birth. Wolf spiders (Araneae: Lycosidae) provide an opportunity to explore this phenomenon since females carry their eggsacs prior to eclosion and, after emergence, carry spiderlings for days as they disperse. During maternal care, mothers may prenatally expose offspring to predator odour cues and potentially influence their posteclosion dispersal when in the presence of these cues. Spiderlings of the wolf spider Tigrosa helluo are eaten by adults of the wolf spider Pardosa milvina. We measured differences in substrate preferences of spiderlings produced from egg-carrying T. helluo females that had or had not been exposed to cues of adult P. milvina. Over a 15-day period we counted the number of offspring climbing on substrates previously walked on by P. milvina, crickets or blank control substrates. For the first 10 out of 15 days, spiderlings of predator-exposed mothers climbed on Pardosa substrates significantly more compared to control mothers. We found no significant spiderling preference in time spent on cricket-cued or control substrates across treatments and no difference in chemical cue substrate preference of the mothers while spiderlings dispersed. Among wolf spiders, vertical climbing and contact with predator-cued substrates can induce adaptive tonic immobility (freeze response) that has been associated with increased survival in the presence of live predatory lycosids. Spider predator cues may prime spiderling antipredator behaviour either directly through prenatal exposure in the eggsac or indirectly by modifying the mother's behaviour prior to eclosion, but we found no evidence of mother substrate preference influencing spiderling distribution during dispersal.

Tadpoles detect chemical signals released from predators and conspecifics, as well as those present in the environment, and adjust their behavioral responses. This study evaluated the swimming activity of Dorbigny’s Toad (Rhinella dorbignyi (Duméril and Bibron, 1841)) tadpoles exposed to chemical signals, including cues from a predator fish, the marbled swamp eel (Synbranchus marmoratus Bloch, 1795), and an injured conspecific; sublethal concentration of insecticide cypermethrin; and their combination. Swimming behavior (total distance moved, mean speed, global activity, number of contacts between tadpoles) was evaluated in an individual (1) and groups of different size (3, 5, 7, and 10 tadpoles) using a video-tracking software tool. Predator exposure modified behavioral parameters, reducing encounters with predators and, therefore, mortality. Total distance moved and mean speed increased in trials involving 1 tadpole and 3 interacting tadpoles exposed to injured conspecifics, whereas global activity increased in all group sizes, showing that gregarious tadpoles may be affected by alarm cues and their behavior may be disrupted. The insecticide treatments (alone and combined) increased parameters in all group sizes, causing hyperactivity due to its neurotoxic effect. The different responses observed after exposure to alarm cues and environmental signals in the different group sizes modified the normal behavior and the ecological dynamics of gregarious tadpoles.

The aim of the study was to assess which kill site characteristics were selected by a lone wolf living in a protected Mediterranean coastal area near the city of Pisa, Italy, where both wild and domestic ungulates were available as potential prey. Between 2017 and 2019, we monitored the wolf’s predatory behaviour through a combination of camera trapping and active search for kill sites and prey carcasses. The main prey found was the fallow deer (n = 82); only two wild boars and no domestic ungulates were found preyed upon. The features and habitat of kill sites were modelled to test for selection by the wolf. The habitat type of kill site was composed of meadows and pastures (89.3%), woods (7.3%), degraded coastal areas (1.9%), roads and rivers (1.1%), and marshes (0.5%). We calculated their distance from landscape features and ran a binomial generalised linear model to test the influence of such landscape variables. The distance of kill sites from landscape elements was significantly different from random control sites, and a positive selection for fences was found. In fact, the wolf pushed fallow deer towards a fence to constrain them and prevent them from escaping. We also analysed the body condition of predated fallow deer as a percentage of fat content in the bone marrow of the hind legs. Our results revealed the selection of the lone wolf for deer in good body condition. This is a possible outcome of the habitat selection shown by fallow deer in the study area, where fenced open pastures are the richest in trophic resources; therefore, our findings suggest a high efficacy for the lone wolf hunting strategy, but also the adoption of a high risk feeding strategy by deer. This study suggests that a lone predator can take advantage of human infrastructures to maximise its predatory effectiveness.

1. Quantifying the diet composition of apex marine predators such as killer whales (Orcinus orca) is critical to assessing their food web impacts. Yet, with few exceptions, the feeding ecology of these apex predators remains poorly understood. 2. Here, we use our newly validated quantitative fatty acid signature analysis (QFASA) approach on nearly 200 killer whales and over 900 potential prey to model their diets across the 5000 km span of the North Atlantic. 3. Diet estimates show that killer whales mainly consume other whales in the western North Atlantic (Canadian Arctic, Eastern Canada), seals in the mid-North Atlantic (Greenland), and fish in the eastern North Atlantic (Iceland, Faroe Islands, Norway). Nonetheless, diet estimates also varied widely among individuals within most regions. This level of inter-individual feeding variation should be considered for future ecological studies focusing on killer whales in the North Atlantic and other oceans. 4. These estimates reveal remarkable population- and individual-level variation in the trophic ecology of these killer whales, which can help to assess how their predation impacts community and ecosystem dynamics in changing North Atlantic marine ecosystems. 5. This new approach provides researchers with an invaluable tool to study the feeding ecology of oceanic top predators.

La Trobe University Faculty of Science, Technology and Engineering Murray Darling Freshwater Research CentreMDFRC item.Numbers of wading birds are declining throughout the Murray-Darling Basin in Australia, and the loss of wetland habitats to agriculture is the most likely cause. This study describes the foraging of egrets in irrigated rice fields that occur extensively in areas of former wetlands. Tadpoles were the main prey of Great and Intermediate Egrets (Ardea alba and A. intermedia), with insects important secondary prey. Insects were the main prey of Cattle Egrets (A. ibis). Prey capture rates for Great and Intermediate Egrets declined by around 40% between November and January as the rice plants grew froth seediing to mature stages. Cattle Egret prey capture rates did not decline. The abundance of tadpoles and most aquatic insects in the rice fields declined significantly between November and February. All three egret species laid eggs mainly during December and had young in the nest during January arid February. Thus the declining profitability of rice fields as foraging sites coincided with the maximum demand for food by the birds to rear their voting. Rice fields may not be an adequate substitute for natural wetlands for Great and Intermediate Egrets.

As top predators, seabirds can be indirectly impacted by climate variability and commercial fishing activities through changes in marine communities. However, high mobility and foraging behaviour enables seabirds to exploit prey distributed patchily in time and space. This capacity to adapt to environmental change can be described through the study of their diet. Traditionally, the diet of seabirds is assessed through the morphological identification of prey remains in regurgitates. This sampling method is invasive for the bird and limited in terms of taxonomic resolution. However, the recent progress in DNA-based approaches is now providing a non-invasive means to more comprehensively and accurately characterize animal diets. Here, we used a non-invasive metabarcoding approach to characterize the diet of the Westland petrel (Procellaria westlandica), which is an endangered burrowing species, endemic to the South Island of New Zealand. We collected 99 fresh faecal samples at two different seasons and in two different sub-colonies. Our aims were to describe the diet of the Westland petrel, investigate seasonal and spatial variation in the petrels’ diet, and assess potential impacts of the New Zealand fishery industry. We found that amphipods were the most common prey, followed by cephalopods and fish. Our results could be the result of natural foraging behaviour, but also suggest a close link between the composition of prey items and New Zealand’s commercial fishing activities. In particular, the high abundance of amphipods could be the result of Westland petrels feeding on discarded fisheries waste (fish guts). Our results also showed significant differences in diet between seasons (before hatching vs chick-rearing season) and between sampling sites (two sub-colonies 1.5 km apart), indicating plasticity in the foraging strategy of the Westland petrel. Due to its non-invasive nature, metabarcoding of faecal samples can be applied to large numbers of samples to help describe dietary variation in seabirds and indicate their ecological requirements. In our example, dietary DNA (dDNA) provided valuable information regarding the dietary preferences of an iconic species in New Zealand’s unique biodiversity. dDNA can thus inform the conservation of endangered or at-risk species that have elusive foraging behaviours.

Cephalopods have acquired numerous novelties and expanded their habitats to various marine environments as highly agile predators. Among cephalopod novelties, multiple arms are used for complex behaviors, including prey capture. Suckers on arms are innovative features for realizing these arm functions. In addition, tentacles in Decapodiformes (squids and cuttlefishes) are arms specialized in prey capture and tentacular suckers show unique morphologies. However, little is known about the developmental process of sucker formation that should differ between tentacles and other arms. In this study, therefore, sucker formation processes on second arms and tentacles were observed and compared in a bigfin reef squid, Sepioteuthis lessoniana, to reveal the developmental processes forming the unique sucker morphologies, especially in tentacles. Morphological and histological observations of suckers during embryogenesis showed that, in second arms, the sucker-producing area appeared at the most distal part. At the most proximal side of the sucker-producing area, new sucker buds were isolated by invagination of the epithelial tissue. At the proximal arm parts, suckers with functional structures were observed. In tentacles, although the basic sucker formation pattern was similar to that in second arms, sucker formation started at earlier embryonic stages and the number of suckers was drastically increased compared to that in second arms. In addition, although 4 sucker rows were observed at the tentacular club, i.e., the thickest part of a tentacle, our observations suggested that 2 sets of 2 sucker rows are compressed to form the 4 rows. Therefore, the sucker-formation processes are temporally and spatially different between arms and tentacles. In addition, S. lessoniana shows conserved and unique patterns of sucker formation in comparison with previously described species, suggesting that sucker formation patterns were diversified among Decapodiformes lineages. This article is protected by copyright. All rights reserved.

Defensive chemicals are used by plants and animals to reduce the risk of predation through different mechanisms, including toxins that cause injury and harm (weapons) and unpalatable or odiferous compounds that prevent attacks (deterrents). However, whether effective defences are both toxins and deterrents, or work in just one modality is often unclear. In this study, our primary aim was to determine whether defensive compounds stored by nudibranch molluscs acted as weapons (in terms of being toxic), deterrents (in terms of being distasteful), or both. Our secondary aim was to investigate the response of different taxa to these defensive compounds. To do this, we identified secondary metabolites in 30 species of nudibranch molluscs and investigated their deterrent properties using anti-feedant assays with three taxa: rock pool shrimp, Palaemon serenus, and two fish species: triggerfish Rhinecanthus aculeatus and toadfish Tetractenos hamiltoni. We compared these results to toxicity assays using brine shrimp Artemia sp. and previously published toxicity data with a damselfish Chromis viridis. Overall, we found no clear relationship between palatability and toxicity, but instead classified defensive compounds into the following categories: Class I & II - highly unpalatable and highly toxic; Class I - weakly unpalatable and highly toxic; Class II - highly unpalatable but weakly toxic; WR (weak response) - weakly unpalatable and weakly toxic. We also found eight extracts from six species that did not display activity in any assays indicating they may have very limited chemical defensive mechanisms (NR, no response). We found that the different classes of secondary metabolites were similarly unpalatable to fish and shrimp, except extracts from Phyllidiidae nudibranchs (isonitriles) that were highly unpalatable to shrimp but weakly unpalatable to fish. Our results pave the way toward better understanding how animal chemical defences work against a variety of predators. We highlight the need to disentangle weapons and deterrents in future work on anti-predator defences to better understand the foraging decisions faced by predators, the resultant selection pressures imposed on prey, and the evolution of different anti-predator strategies.

BACKGROUND Anthropogenic disturbances are the main threats to nonhuman primates conservation, and infectious diseases may also play a key role in primate population decline. This study aimed to determine the main causes of death in neotropical primates. METHODS A retrospective study of post-mortem examinations was conducted on 146 neotropical primates between January 2000 and December 2018. RESULTS Conclusive diagnoses were obtained in 68.5% of the cases, of which 59 corresponded to non-infectious causes and 41 to infectious diseases. Trauma was the main cause of death (54/100), with anthropogenic stressors caused by blunt force trauma injuries (collision with vehicles) and puncture wound injuries associated with interspecific aggression (dog predation) were the most common factors. Other causes of death included bacterial diseases (27%), followed by parasitic diseases (12%), neoplasms (2%), and viral diseases (2%). CONCLUSIONS Free-ranging primates were mostly affected by non-infectious causes, while captive primates were by infectious conditions.

Large groups of animals aggregate around resource hotspots, with group size often influenced by the heterogeneity of the environment. In most cases, the foraging success of individuals within groups is interdependent, scaling either constructively or destructively with group size. Here we used biologging tags, acoustic prey mapping, passive acoustic recording of social cues and remote sensing of surface currents to investigate an alternative scenario in which large, dense aggregations of southeast Atlantic humpback whales, Megaptera novaeangliae, and northeast Pacific blue whales, Balaenoptera musculus, were each associated with ephemeral krill aggregations large enough such that their availability to predators appeared to be influenced more by environmental features than by consumption, implying independence of group size and consumption rates. We found that the temporal scale and spatial extent of oceanographic drivers were consistent with the temporal scale and locations of predator aggregations, and additionally found that groups formed above bathymetric features known to promote zooplankton concentration. Additionally, we found calling behaviour counter-indicative of competition: blue whale foraging calls were anomalously high during observed aggregation time periods, suggesting signalling behaviour that could alert conspecifics to the location of high-quality resources. Modelled results suggest that the use of social information reduces the time required for individuals to discover and exploit high-quality resources, allowing for more efficient foraging without apparent costs to the caller. Thus, rorqual whales foraging in these environments appear to exhibit a social foraging strategy whereby a behaviour with negligible individual costs (signalling) provides information that enhances group foraging efficiency. The population density dependence of this social foraging strategy may help explain why some rorqual species were at first slow to recover from human exploitation, but have since increased more rapidly.

Introduced large herbivores have partly filled ecological gaps formed in the late Pleistocene, when many of the Earth's megafauna were driven extinct. However, extant predators are generally considered incapable of exerting top-down influences on introduced megafauna, leading to unusually strong disturbance and herbivory relative to native herbivores. We report on the first documented predation of juvenile feral donkeys Equus africanus asinus by cougars Puma concolor in the Mojave and Sonoran Deserts of North America. We then investigated how cougar predation corresponds with differences in feral donkey behaviour and associated effects on desert wetlands. Focusing on a feral donkey population in the Death Valley National Park, we used camera traps and vegetation surveys to compare donkey activity patterns and impacts between wetlands with and without cougar predation. Donkeys were primarily diurnal at wetlands with cougar predation, thereby avoiding cougars. However, donkeys were active throughout the day and night at sites without predation. Donkeys were ~87% less active (measured as hours of activity a day) at wetlands with predation (p < 0.0001). Sites with predation had reduced donkey disturbance and herbivory, including ~46% fewer access trails, 43% less trampled bare ground and 192% more canopy cover (PERMANOVA, R2 = 0.22, p = 0.0003). Our study is the first to reveal a trophic cascade involving cougars, feral equids and vegetation. Cougar predation appears to rewire an ancient food web, with diverse implications for modern ecosystems. Our results suggest that protecting apex predators could have important implications for the ecological effects of introduced megafauna.

We here report the first dynamic event of predation and defensive behavior in Microcaecilia nicefori provoked by Micrurus dumerilii in Armero, Tolima, Colombia, and we also provide a compendium of all the available literature records of caecilians being preyed upon by snakes in the Neotropic.

Leptodeira snakes are frog predators. Here I report the predation of the Mexican treefrog Smilisca baudinii by L. polysticta and I provide quantitative data on the distress call emitted by the treefrog. Besides, I compare some Leptodeira species' prey information based on previous records.

The Asiatic wild dog or ‘dhole’ (Cuon alpinus) is an apex predator inhabiting south and south-east Asia. Lack of detailed information on its biology has designated it as one of the lesser-known species throughout its distributional range. Herein, we report the presence and activity pattern of dholes in Debrigarh Wildlife Sanctuary, Odisha, India through camera trap surveys from 25th August 2018 to 29 December 2019. From a total of 3150 camera-trapping nights at 123 sampling sites, we obtained 28 independent detections of dhole at nine sites. The activity of species is diurnal, especially in the morning and its activity seems to coincide with its major prey. Debrigarh wildlife sanctuary could be an important habitat and source population for dholes in India, because of abundant prey, lack of disturbance and good habitat connectivity with the central Indian landscape.

Holcosus gaigeae es una lagartija de tamaño pequeño y cuerpo moderadamente robusto que tiene una distribución restringida a la porción Mexicana de la Península de Yucatán. La información existente acerca de su ecología e historia natural es limitada. En este escrito se presentan observaciones de depredación, dieta y reproducción de H. gaigeae en diferentes porciones de los estados de Yucatán y Campeche, en México, las cuales aportan nueva información acerca de los aspectos ecológicos de esta especie.

European bee-eater (Merops apiaster Linnaeus, 1758; Coraciiformes: Meropidae) is known as a bee-predator, but its food spectrum is variable and depends on the current supply. This is the first study focused on the ants (Hymenoptera: Formicidae) as important prey in the diet of the European bee-eater. In 2017, 9,604 insect prey was obtained from pellets gained from two colonies breeding: (1) underground of a grazed sand dune (Radvaň nad Dunajom) and (2) in the sandy wall (Gabcikovo) without pasture, both in southern Slovakia. Five ant taxa were identified, the list of ants in the bee-eater’s diet was expanded by three taxa Lasius sp., Camponotus vagus (Scopoli, 1763) and Liometopum microcephalum (Panzer, 1798). In summary, ants represent the second most abundant family (12.35 %) of total prey. Compared to adults, nestlings (15.04 %) ate significantly more ants than adults (10.97 %). To study the ants’ composition in the diet of bee-eater near to different types of habitats, the pellets of nestlings were chosen because they more accurately reflect the sources of insect during the breeding season. Differences in the feeding of the European bee-eater nestlings between the grazed and the non-grazed locality were confirmed, where Lasius sp. and Tetramorium sp. highly correlated with grazing site. Moreover, nestlings ate significantly more ants in the area, where an open habitat was managed by grazing (6.55 vs. 15.04 %). The presented research indicates the importance of traditional pastures in the country for ants and also for bee-eaters. These ecosystem engineers are likely to find more microhabitats on the pastures, which has also been reflected in the diet of the nestlings breeding on the grazed site.

Death feigning is an adaptive defence strategy that improves survival rates, often by decreasing predation risk. Although death-feigning behavior has been documented in many animals, the study on insects has gradually attracted more focus. Previous study reported two weevil species—Eucryptorrhynchus scrobiculatus (ESCR) and E. brandti (EBRA)—considered forestry pests, and exhibited death-feigning behavior. To examine the trade-off between the particular anti-predator behaviors and prey fitness, we endeavoured to experimentally determine how temporal (age), activity, and diurnal rhythm may affect death-feigning duration. We found that the death-feigning duration was gradually increased and then decreased with the increased age, and the variation appeared on 5 days. The death-feigning duration during the day (the zeitgeber time, ZT12) was shorter than during the night (the zeitgeber time, ZT5 and ZT24) for both species. However, ESCR weevils with lower locomotor activity displayed longer death-feigning durations. The significant correlations between age, activity, diurnal rhythm, and death feigning would provide the timescale when death-feigning pests were likely to be caught by natural enemies, which help us fully understand the behavioral rhythm to develop novel methods of biological pest control.

Toucans are known for their predatory behavior, and urbanization can provide encounters with potential prey species that they would probably not meet in their usual natural habitats. Here, we describe a series of events of the Channel-billed Toucan (Ramphastos vitellinus) preying on eggs and nestlings of the Pale-breasted Thrush (Turdus leucomelas). The events occurred in a large forest fragment surrounded by an urban matrix in the Amazonian city of Manaus, Brazil. Urbanization has led to new challenges for many animals, including birds. The events reported here exemplify some of these challenges, such as the adaptation of a toucan or a population of toucans to exploit different food resources and find new prey in a modified environment, and the pressure of a new predator on the reproductive success of a thrush population. These new challenges may result in other adaptations and behaviors that must be investigated, as they can reveal patterns, impacts, or novelties on bird species and even on avian communities related to urbanization.

Los lenguados son importantes en el flujo de energía de los estuarios, el cual está influenciado por la dinámica de las variables ecológicas y ambientales de estos ecosistemas. Esta investigación proporciona una evaluación de la influencia que tienen las variaciones ambientales (espaciotemporales) en la dieta de Citharicthys gilberti en la Bahía de Buenaventura. Se examinaron un total de 92 estómagos correspondientes a sitios con diferentes características ambientales dentro de la Bahía. Se determinaron índices de alimentación para hacer una caracterización trófica y evaluar las interacciones entre los hábitos tróficos y las variables ambientales. Los resultados muestran que esta especie es en gran medida un depredador oportunista. Las presas que representaron la mayor importancia relativa dentro de la dieta de C. gilberti fueron los crustáceos y los peces. El consumo de crustáceos fue mayor en la época seca y en la zona externa, siendo influenciado significativamente por variaciones en el pH y la transparencia. Por otra parte, el consumo de peces fue constante todo el año independientemente de las variaciones ambientales. Así mismo, los nematodos y los poliquetos fueron presas secundarias y los huevos y moluscos presas secundarias o accidentales y no presentaron diferencias espaciotemporales. Los peces bentónicos son de vital importancia en el ecosistema estuarino, ya que proporcionan un intercambio energético entre el hábitat demersal y la columna de agua, reflejando no solo los efectos de las variaciones ambientales, sino también, la dinámica de las especies relacionadas tróficamente.

Autotomy is a drastic antipredator defense consisting of the voluntary shedding of a body part to escape from the predators. The loss of a body part may impair locomotion, feeding or mating, so animals may face a higher predation risk shortly after autotomy. Thus, until regeneration is completed, prey may adjust their behavior to reduce predation risk, and this could involve secondary costs. We assessed the effect of tail loss on the antipredator behavior of wall lizards (Podarcis muralis), comparing the behavior of tailed and tailless individuals exposed to a predatory snake (Coronella austriaca) scent, under controlled experimental conditions. Tailless lizards spent significantly more time performing behaviors with antipredatory significance (e.g., moving slowly), whereas tailed individuals performed exploratory walking for significantly more time. Moreover, tailless lizards spent more time basking, which probably increases the effectiveness of their cryptic design and decreases detection by predators. Lizards intensified the tongue flick rates when exposed to a pungent control or snake scents, as compared to their response to a neutral control. Besides, both tailed and tailless lizards intensified some aspects of their antipredator behavior (walking slowly and avoiding refuge use) when exposed to snake scent, which indicates discrimination of the smell of predatory snakes. Lizards decreased refuge use when exposed to predator scents, probably because the refuges are evaluated as unsafe due to a high concentration of snake scents. To conclude, our experiments showed that, after losing their tails, wall lizards modify their behavior in a way that likely minimizes predation risk.

Intraspecific variation in social behaviour is often observed among animal populations. Local predation risk can be a key driver of these differences, with populations that are exposed to greater threat typically showing greater aggregation and reduced intraspecific aggression. The Trinidadian guppy, Poecilia reticulata, is found in populations that vary dramatically in predation risk and show greater grouping and reduced agonism in high-predation populations compared to low-predation populations. The neurohormonal mechanisms that underpin these differences in behaviour across populations remain unknown and elucidating these mechanisms may help us to understand the evolution of behavioural diversity in this species. We predicted that guppies naturally exposed to higher predation risk would show greater expression of the isotocin system and reduced expression of the vasotocin system when compared to low-predation fish, because these peptides are thought to promote gregariousness and aggressivity respectively. We collected guppies of both sexes from high- and low-predation sites, replicated in two different Trinidadian rivers, and measured the brain gene expression of isotocin and vasotocin along with their central receptors. Contrary to our prediction, we found that high-predation guppies showed greater expression of vasotocin, while we did not find evidence that the populations differed in isotocin expression, nor in the expression of the receptors. These results support the hypothesis that vasotocin may act as a neural substrate for social variation in fishes but call into question generalisations about its specific role across species.

To improve reproductive success and maximize offspring survival, bird parents have to deal with the threat of nest predation while caring for nestlings, which necessarily involves their presence near the nest. On the other hand, predators may use cues to find nests, such as conspicuousness of the nest, nestlings, or parents. Although conspicuousness may confer advantages for males and females in some contexts (e.g., individual quality and mate choice), it may also confer survival costs for individuals or their offspring, especially when predators are visually oriented. In this study, we carried out a field experiment to test if visual cues attract predators to nests and impose a higher risk to eggs. By using painted styrofoam balls and artificial nests baited with Quail eggs, we asked if the presence of conspicuous or cryptic visual cues increased the nest predation risk. Based on our experimental results, we rejected the hypothesis that visual cues increase nest predation. The presence of visual cues in the nest did not impose additional risks to eggs. This may be explained by particularities of the study area, such as the possibility that predators at our site are mostly olfactory oriented. Furthermore, additional factors associated with parental care (e.g., parental movements around nests), which were not evaluated here, may have a greater impact on birds’ nest predation. Our study is consistent with previous studies that found no effects of individual factors (e.g., visual cues) on nest predation, emphasizing the complexity of these events.

Although selecting advantageous sleeping sites is crucial for nonhuman primates, the extent to which different factors contribute to their selection remains largely unknown for many species. We investigated hypotheses relating to predator avoidance, food access, and thermoregulation to explain the sleeping behavior of Bale monkeys (Chlorocebus djamdjamensis) occupying a degraded fragmented forest, Kokosa, in the southern Ethiopian Highlands. We found that the study group reused 11 out of 20 sleeping sites used during the 42 study days over a 6-month period. Sleeping sites were usually close to the last feeding trees of the day (mean distance =15.2 m) and/or the first feeding trees of the next morning (mean distance = 13.5 m). This may reflect an attempt to maximize feeding efficiency and reduce travel costs. Compared to the mean trees in the study area, sleeping trees were significantly shorter. Bale monkeys selected sleeping places in trees with high foliage density above and below them, lending support to the hypothesis that they select sleeping places that can conceal them from predators and at the same time offer shelter from cold weather. The monkeys also frequently huddled at night. Our results suggest that predator avoidance, access to food resources, and thermoregulation all likely influence the selection of sleeping sites by Bale monkeys.

Livestock guardian dogs (LGDs) are efficient at controlling predation upon livestock. LGDs create a safer landscape for livestock through accompaniment and the reduction of the abundance and distribution of wild carnivores. However, the effects of LGDs on livestock behavior, group dynamics, and use of space remain understudied. To understand LGDs’ impact on sheep behavior and group dynamics, and using a natural experiment approach, we worked on two sheep farms that differed in the use of LGDs to control predation. We used the focal sampling technique to observe sheep behavior; in addition, we obtained information about group size and nearest neighbor distance. Nutritional quality and habitat selection were also assessed. For each individual, we calculated the proportion of time invested in behavioral categories (scanning, feeding, resting, and traveling), and categories between properties were contrasted with the nonparametric U-test, as well as features related to group dynamics, vegetation structure, and food quality. Furthermore, we investigated the effect of LGDs and other management and biological variables on sheep behavior and group properties. In close proximity to LGDs, sheep spent more time in scanning while time allocated to feeding decreased; however, feeding time did not change based on its presence. Moreover, LGDs’ company led to the formation of larger sheep groups and individuals closer to each other. Sheep together with LGDs selected habitats with limited plant cover, which allows animals greater visibility. Lastly, we suggest that the ability of LGDs to maintain larger and more cohesive groups in open areas, as well as with more vigilant animals, could increase livestock responsiveness to predator presence, thus helping to reduce probability of predation on sheep and, in consequence, reducing the necessity of killing wild species in retaliation.

Leaving the nest is a key transition in the life of altricial birds, whereby fledging decisions should depend on multiple factors, including the risk of predation. High postfledging predation risk may favour fledging at a more advanced stage of development, if more developed fledglings are better at escaping predation, or together with others. While comparative studies have highlighted the role of predation risk for between-species variation in the timing of fledging, drivers of within-species variation in fledging behaviour remain largely unknown. We presented owl models near blue tit, Cyanistes caeruleus, nests during the first half of the day throughout the fledging period to simulate an increased risk of postfledging predation. Using an automated monitoring system, we then recorded the precise fledging times of 595 nestlings from 105 nests (52 predator-treated, 53 control nests). Contrary to our predictions, the predator presentations did not affect the age at which nestlings fledged, the time of day of fledging or other aspects of fledging behaviour. The tendency to fledge together with siblings was affected, but the effect was in the opposite direction to that expected, with nestlings exposed to the predator treatment being more likely to fledge alone. Parents visited predator-treated nests less often, but this effect diminished over the course of the morning. We suggest several explanations for why the behavioural responses to the predation risk manipulation were generally limited.

Greater sage-grouse (Centrocercus urophasianus, hereafter, sage-grouse) have experienced habitat loss from expansion of juniper (Juniperus spp.) woodlands into sagebrush steppe. Sage-grouse avoid high levels of juniper cover (> 10% cover) but can vary in response to cover > 0–10%. Selection patterns by hens may be affected by differences in resource needs or predation risk between brooding (i.e., hens with chicks) and nonbrooding hens (i.e., hens without chicks). We investigated whether reproductive status influenced habitat selection at multiple spatial scales among hens in a landscape undergoing juniper expansion. We conducted our study during the 2017–2018 breeding seasons in southwestern Idaho. We collected habitat data at broad spatial extents (hereafter, macroscales) using remotely sensed layers and at a fine spatial extent (hereafter, microscale) with field-based surveys. We collected data at used and available locations for 11 brooding and 19 nonbrooding hens at macroscales (n = 2 059 locations) and microscales (n = 181 locations). At the macroscales, both reproductive groups avoided cover class II (> 10–20% juniper cover) and III (> 20% juniper cover) but nonbrooding hens were 2.8 × more likely to select cover class I (> 0–10% juniper cover) than brooding hens. In addition, nonbrooding hens selected wetlands dominated by woody vegetation (e.g., willows), whereas brooding hens selected wetlands dominated by herbaceous vegetation. At the microscale, brooding hens were 22.1 × more likely to select taller nonsagebrush shrubs than nonbrooding hens. Our results support our prediction that nonbrooding hens were more likely to select cover class I juniper than brooding hens. Our results help inform more targeted treatment whereby removal of juniper around wetlands and mesic habitats with taller nonsagebrush shrubs may be the most beneficial because increasing the availability of these habitats could positively influence survival of chicks and adults.

Salt cedar (Tamarix spp. L), is found across Texas and the western United States, primarily near riparian areas. Introduced in the 1800s as an ornamental plant, salt cedar escaped domestic gardens, invading native rangelands. Mechanical and chemical control options for salt cedar are available, but effective control can be difficult and cost prohibitive. Sheep and goats will readily consume salt cedar after exposure at weaning, and goats readily consume the plant when released on rangelands. Unfortunately, sheep and goats are not a viable option in many areas due to predation or lack of appropriate fencing. The objectives of this study were to determine if cattle would consume salt cedar at a similar level (body weight basis) as sheep and goats and to determine if preconditioning improved acceptance of salt cedar by cattle. Angus-Hereford cross heifers (n = 15), Rambouillet lambs (n = 15), and Boer-Spanish cross kids (n = 15) were placed in individual pens for 21 d and fed salt cedar leaves and tender stems daily. For the first 21 d, eight head from each species were fed a basal diet and salt cedar while 7 head only received the basal diet. The amount of salt cedar in the diet was increased from 5% of the diet to 10% of the diet after 7 d of feeding and fed until d 21. From d 22 to 28 both naive and familiar animals were fed salt cedar daily. All animals readily increased intake of salt cedar. By d 7, cattle, sheep, and goats consumed the plant, but intake varied daily for cattle and sheep. After the first 7 d, goats consistently ate more (P

Strategies that mitigate predation, whether proactive or reactive, can nevertheless impose significant ‘nonconsumptive’ costs on prey species. Here we used data from two wild vervet monkey, Chlorocebus pygerythru,s groups to assess whether the detection of predators affected their subsequent behaviour to the detriment of their short-term foraging effort. Encounters with the three predator classes present at our study site were frequent and there was evidence that animals were more likely to shift to predator-focused vigilance, which was modulated by alarm call intensity, but not predator type, in the hour following detection. Nevertheless, and against expectation, there was no detectable shift in overall levels of vigilance, which remained low, interindividual distances, travel bearing and, consequently, effort put into foraging. We consider this surprising imperturbability by our study groups in the context of population group size, as our groups are large and have correspondingly lower levels of individual vigilance, as well as in terms of the constraints imposed by small, overlapping territories and frequent predator encounters. Finally, we advocate for increased consideration of the responses of the predators themselves to detection by their prey.

Herbivory, and thus, the ability to acquire energy from consuming plant material, evolved numerous times independently within vertebrates. Several mechanical solutions for processing plant material have emerged along with the independent rise of herbivorous feeding strategies. Comparative studies of these mechanical solutions suggest that herbivory might generally relate to “improved” and hence comparatively effective food processing mechanisms, often involving the jaws. Such processing behaviours involving the jaws can be referred to as chewing sensu lato. While herbivory is relatively common among vertebrates, it is generally believed that salamanders exclusively feed on other animals (i.e., carnivory). Further, it had been hypothesized that salamander food processing is limited to “simple” and comparably ineffective puncture crushing movements (i.e., opening and closing movements of the jaws in combination with pointed teeth), which may not be efficient enough to break down plant material. However, sirenid salamanders (i.e., dwarf sirens and sirens, genera Pseudobranchus and Siren respectively) have long been reported to consume large amounts of plant material besides feeding on animal prey. Additionally, some sirenids have only recently been shown to apply complex three-dimensional chewing behaviours. These complex chewing behaviours could potentially enable the mechanical breakdown of plant material. Here we comparatively study sirens with particular regards to the form and function of their feeding apparatus and their feeding habits. We demonstrate that sirenids generally seem to apply complex chewing mechanisms and, in fact, consume both plant- and animal foods. Comparative gastrointestinal morphology, however, suggests that among sirenids, only sirens are apt to digest and extract energy from plant material, suggesting that dwarf sirens may not benefit from the energy of their “plant food”, while sirens appear to be facultative herbivorous - or better, omnivorous. Consequently, our results indicate that some salamanders can eat, process, and acquire energy from plant material, hence, contradicting the commonly accepted idea that salamanders are generally carnivorous.

Familiarity between members of the same group is predicted to play a role in many biological processes. Familiarity can facilitate recognition, aggregation, communication, coordination and cooperation between group members. We tested a path of interrelated hypotheses on the effect of familiarity on survival, resource acquisition, predator avoidance and cooperation. We predicted that individuals with familiar members in their group would have a higher survival, acquire resources faster, avoid predators more easily and perform more cooperative actions. We used data from an online video game (Dead by Daylight) where small groups of four players (i.e. prey) must exploit resource patches while avoiding a predator. Prey can help fellow prey when the predator catches them (cooperation). Using a video game as a study system provided access to a large behavioural data set that would otherwise be difficult to obtain in nature. Using path analysis, we found evidence that coordinated resource acquisition and helping behaviours increased with the number of familiar individuals in the group. However, more cooperative actions increased their encounters with the predator and thus reduced their survival. When accounting for all indirect effects of familiarity on survival (through resource acquisition, cooperation and predator–prey encounters), familiarity had a small indirect net positive effect on survival.

Emperor Frederick II’s early thirteenth-century book on falconry, De arte venandi cum avibus, is probably the most famous single source for scholars who survey the state-of-the-art in natural sciences in medieval times. Most of the research on his book has focused on the marginal illustrations featuring about 80 bird species. However, the book contains a large amount of ethological, ecological, morphological and faunistic knowledge about bird fauna. Frederick was also one of the first to conduct experiments with birds. Here, we describe the ornithological experiments and observations of Frederick and evaluate them from the perspective of modern ecology. In many contexts, Frederick expressed criticism of Aristotle and his work Liber Animalium. Frederick’s observation upon the geographical variation of species was partially in contrast to the Aristotelian typological or essentialist species concept. This is an important finding from the point of view of the western history of biology. De arte venandi cum avibus demonstrates Frederick’s deep knowledge of the ecology, morphology and behaviour of birds. This knowledge he gained via his long practice with falconry. The love of falconry made Frederick an early proponent of empiricism, and De arte venandi cum avibus was actually the most important achievement of empirical zoology in the thirteenth century.

Accurate information on diet composition is central to understanding and conserving carnivore populations. Quantitative fatty acid signature analysis (QFASA) has emerged as a powerful tool for estimating the diets of predators, but ambiguities remain about the timeframe of QFASA estimates and the need to account for species-specific patterns of metabolism. We conducted a series of feeding experiments with four juvenile male brown bears (Ursus arctos) to (1) track the timing of changes in adipose tissue composition and QFASA diet estimates in response to a change in diet and (2) quantify the relationship between consumer and diet FA composition (i.e., determine "calibration coefficients"). Bears were fed three compositionally distinct diets for 90-120 days each. Two marine-based diets were intended to approximate the lipid content and composition of the wild diet of polar bears (U. maritimus). Bear adipose tissue composition changed quickly in the direction of the diet and showed evidence of stabilization after 60 days. During hibernation, FA profiles were initially stable but diet estimates after 10 weeks were sensitive to calibration coefficients. Calibration coefficients derived from the marine-based diets were broadly similar to each other and to published values from marine-fed mink (Mustela vison), which have been used as a model for free-ranging polar bears. For growing bears on a high-fat diet, the temporal window for QFASA estimates was 30-90 days. Although our results reinforce the importance of accurate calibration, the similarities across taxa and diets suggest it may be feasible to develop a generalized QFASA approach for mammalian carnivores.

Different aspects of breeding ecology of Common Tailorbirds (Orthotomus sutorius) were studied between February and September 2015 at Jahangirnagar University Campus, Dhaka, Bangladesh. Among the 35 active nests found, 25 nests were observed until fledging. Eight tree species belonging to seven families were utilized for nest building and nests were built on average 0.85 ± 0.68 m above the ground. Average clutch size was 3.12 ± 0.97 eggs per nest. The incubation period lasted 14.04 ± 1.05 days. Hatching rate of Common Tailorbird eggs was 33.3%, with mean of 1.13 ± 0.90 chicks fledged per nest. In general, overall nesting success was 36%. Four Tailorbird nests were parasitized by Plaintive Cuckoo Cacomentis merulinus, and all nests were predated or damaged, resulting in breeding success of Plaintive Cuckoo as 0%. The study did not find any influence of nest height and distance to the nearest road on nest predation. Because Common Tailorbird uses diverse plants for nesting, such adaptation can enhance their chance to thrive in human-dominated habitats of Bangladesh.

Most viperids are ambush predators that primarily use venom to subdue prey, employing a strike-release-trail hunting strategy whereby snakes follow the unique scent of envenomated prey to locate carcasses they have bitten and released. In addition to killing prey, rattlesnakes (like most carnivores) will also opportunistically scavenge carrion. This scavenging strategy likely includes the occasional consumption of carcasses killed by other snakes (i.e., kleptoparasitism). In areas with high densities of other pitvipers, utilizing the unique scent of animals envenomated by other snakes might be a viable alternative foraging strategy. We evaluated this possibility experimentally using a series of captive behavioural trials on prairie rattlesnakes (Crotalus viridis) to determine whether conspecific or heterospecific (C. scutulatus, C. ornatus) envenomation cues might increase the likelihood of kleptoparasitism. Rattlesnakes did not prefer envenomated prey over nonenvenomated prey, nor did they prefer venom cues of one species over another. Although they did frequently scavenge carcasses, in the absence of striking, snakes generally located carcasses using random searching movements instead of scent trails. Additionally, the amount of time rattlesnakes spent investigating carcass trails did not differ significantly among treatments, suggesting that striking, and the resultant formation of a chemical search image of prey, is more crucial to trailing behaviour than venom cues. Moreover, a high degree of behavioural variation among individuals was observed, suggesting that scavenging and kleptoparasitism in rattlesnakes is more complex than previously realized, and making generalizations about these behaviours is challenging.

Previous research on Cyrba algerina (Araneae, Salticidae) has shown this jumping spider expresses predatory specialisation with respect to spiders as prey as well as inter-population variation in responsiveness to prey-spider odour. However, this earlier research pertained to a single prey species (Oecobius machadoi) and only field-collected C. algerina individuals were tested. Here we extend the previous research by using laboratory-reared, as well as field-collected, individuals of C. algerina and also by using another prey-spider species, Zelotes thorelli, as well as O. machadoi. Two localities in Portugal are considered, Sintra where C. algerina and both prey species are abundant and Tavira where C. algerina is present but neither prey species has been found. In olfactometer experiments, field-collected C. algerina individuals from Sintra, but not Tavira, were attracted to the odour of both prey species. Next, we tested the response of laboratory-reared Sintra C. algerina individuals that had been maintained with no prior experience with the odour of either prey species. We found no evidence of laboratory-reared individuals being attracted to the odour of either prey species in the olfactometer. These findings suggest that prior experience mediates responsiveness of C. algerina to the odour of local prey.

The Chinese pangolin (Manis pentadactyla) is a critically endangered mammal with a highly specialized diet. To enhance nutritional knowledge of its diet, we analyzed the colony composition of a nest of Polyrhachis dives ants, which is the key natural prey in the Chinese pangolin's diet. In addition, we determined the nutrient composition of the total colony compared with adult ants. Nutrients quantified in this study included: crude protein, crude fat, carbohydrate, and amino acids, minerals, and vitamins, as well as formic acid and chitin, which have not been reported in previous diet studies. Our results showed that the colony consisted of adults (82%), pupae (10%), larvae (7%), and eggs (1%) (fresh mass). Both the total colony and adult ants, respectively, contained high concentrations of crude protein (62.97% and 64.68%), chitin (49.25% and 60.40%), crude fat (10.12% and 9.91%) (dry matter basis), and formic acid (2.06% and 3.07%) (fresh mass). This implies that Chinese pangolin might prefer prey with high protein, high chitin, low fat, and low formic acid content. Colony and adult ants differed in chemical composition in many aspects, thus it might be unsuitable to feed Chinese pangolin with only adult ants. Chitin and formic acid may play important roles in the diet and selectivity of Chinese pangolin. This study provides reference information that may be useful for developing better artificial diets with more comprehensive nutrient compositional data to meet the nutritional requirements of the Chinese pangolin under managed feeding programs.

Ecologists increasingly recognize the importance of habitat selection as a multi-level, hierarchical process, but individual-level variation in selection patterns have yet to be fully evaluated within populations of large carnivores. We assessed jaguar (Panthera onca) selection of forest across seasonally variable forest availability in the Pantanal region of South America. Using resource selection functions (RSF), we evaluated the importance of forest cover for jaguars in a heterogeneous, dynamic landscape, and how seasonal variability in habitat availability influences habitat selection and predation patterns. A multi-level hierarchical analytical framework revealed that jaguars increasingly selected forest cover as availability of other habitats declined due to seasonal flooding. At the population range level, jaguars selected water, forest, and bushy grassland comparably during the dry season, and bushy grassland, forest, and flat grassland during the wet season. At the home range level, bushy grassland and forest were selected during both seasons. Jaguars killed prey animals with comparable frequency across forest, water, and bushy grasslands during the dry season, with more preference detected for forest and avoidance of grasslands. During the wet season, jaguars killed prey disproportionately to their availability in forest and bushy grasslands. These results clearly indicate that jaguars undergo marked dynamic shifts in habitat and kill site selection in response to seasonal flooding, with forest patches becoming more important as the availability of other habitats decreases. Land conservation efforts need to consider variability in jaguar-landscape dynamics associated with seasonal flooding, given increasing pressure to modify native landscapes to more open livestock grazing areas.